Automated breast ultrasound equipment and methods using enhanced navigator aids

ABSTRACT

A method and system acquiring, processing and displaying breast ultrasound images in a way that makes breast ultrasound screening more practical and thus more widely used, and reduces the occurrence of missing cancers in screening and diagnosis, using automated scanning of chestwardly compressed breasts with ultrasound. Enhanced, whole-breast navigator overview images are produced from scanning breasts with ultrasound that emphasize abnormalities in the breast while excluding obscuring influences of non-breast structures, particularly those external to the breast such as ribs and chest wall, and differentiating between likely malignant and likely benign abnormalities and otherwise enhancing the navigator overview image and other images, thereby reducing the time to read, screen, and/or diagnose to practical time limits and also reduce screening or diagnostic errors.

REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Ser. No. 14/555,408, filed onNov. 26, 2014 (now U.S. Pat. No. 10,251,621 issued on Apr. 9, 2019),which is a continuation-in-part of (i) International Application No.PCT/US14/67758, filed on Nov. 26, 2014, and (ii) U.S. Ser. No.14/448,607, filed on Jul. 31, 2014, which is now U.S. Pat. No. 9,439,621issued on Sep. 13, 2016.

U.S. Ser. No. 14/448,607 claims the benefit of U.S. ProvisionalApplication No. 61/910,139, filed on Nov. 29, 2013, and U.S. ProvisionalApplication No. 62/003,448, filed on May 27, 2014, and is acontinuation-in-part of (I) International Application No.PCT/US14/48897, filed on Jul. 30, 2014, and (II) U.S. Ser. No.14/084,589 filed on Nov. 19, 2013.

U.S. Ser. No. 14/084,589 is a continuation-in-part of U.S. Ser. No.14/044,842, filed on Oct. 2, 2013(now U.S. Pat. No. 9,826,958 issued onNov. 28, 2017), which claims the benefit of U.S. Provisional ApplicationNo. 61/709,136, filed on Oct. 2, 2012; U.S. Provisional Application No.61/728,166, filed on Nov. 19, 2012; U.S. Provisional Application No.61/830,241, filed on Jun. 3, 2013; and U.S. Provisional Application No.61/860,900, filed on Jul. 31, 2013, and is a continuation-in-part ofU.S. Ser. No. 12/839,371, filed on Jul. 19, 2010. The entire contents ofeach of the referenced applications are hereby incorporated byreference.

FIELD

This patent specification relates to breast ultrasound equipment andmethods that produce and use whole-breast navigator aids and pop-upsthat improve the operation and results of medical ultrasound systems.One of the objectives is to speed up acquiring ultrasound measurements,reduce the time to find breast abnormalities while improving accuracy,and generally improve patient flow and accuracy of results. Theequipment and methods are particularly helpful for women with breaststhat are relatively dense to x-rays and therefore may not be screened,diagnosed, or treated as effectively with the use of standard x-raymammograms.

BACKGROUND

In the US, the expected statistical figures for breast cancer in 2013are estimated at approximately 230,000 new cases and 40,000 deaths. Themortality rate can be lowered if breast cancer could be detected in anearlier stage. Screening with X-ray mammography has been the goldstandard for early detection of breast cancer. However, it is believedthat in about 40% of the screening population typically more than 50% oftheir breasts are made up of dense fibro-glandular breast tissues thattend to obscure abnormalities in X-ray mammograms. Recent clinicalstudies report that this “dense breast” gap could be economically andsufficiently dealt with using breast ultrasound. Currently, anautomated-scan breast ultrasound system that received USFDA approval forbreast cancer screening uses a chestward compression automated scanningprocedure with an ultrasound transducer contacting the breast through amembrane. Such system is available from GE Healthcare under the nameInvenia ABUS, and a similar system is believed available at least inEurope from Siemens Healthcare. A breast ultrasound system usingscanning that is partly automated and partly manual, where thetransducer contacts the breast through a camisole and a nipple pad, isreported by SonoCine, Inc. of Reno, Nev. A system in which thetransducers are acoustically coupled with the breast through a liquidand produces CT-like slice images of the breast, is reported byDelphinus Medical Technologies, Inc. of Plymouth Mich.

There are two major challenges facing practical breast cancer screeningmodalities. The first is cost, which can be measured as the cost of theactual examination and assessment of the results, and as the cost perdetected cancer. Since breast cancer has low prevalence rate such thatone cancer is generally found in 200 to 300 asymptomatic patientsscreened, the per patient screening cost must be kept low, currentlytypically to the range of $100-$200 in the U.S., in order to achieve areasonable cost per cancer detected (i.e. $20,000 to $60,000 range).This cost range generally translates to limiting typicalreading/interpretation time to about 3 minutes per patient, using anautomated scanning system with a throughput of over 2,000 patients peryear. For standard screening x-ray mammography, where only 4 new imagesare generated per patient at a screening examination in typical U.S.practice, this 3-minute interpretation time goal is relatively easilymet. However, for current commercial breast ultrasound screeningexaminations, where hundreds or even thousands of new two-dimensional(“2D”) thin-slice images per patient are obtained under chestwardcompression, in planes transverse to the coronal plane (often called“original” images), the goal of 3 minutes of reading/interpretation timeis difficult to meet. An associated reading method can be used byconfiguring the original thin-slice images first into coronal thin-sliceimages and then into composite coronal thick-slice images, e.g., 2-30coronal thin-slice images into one thick-slice image, so that a user canbetter search for abnormalities and better manage thereading/interpretation time. See for example U.S. Pat. No. 7,828,733,where the coronal thick-slices method is discussed. However, this methodis still not quite fast enough, nor does it satisfactorily solve the“oversight” challenge described immediately below.

The second major challenge of breast cancer screening is “oversight,”i.e., overlooking obvious cancers. A delay in cancer detection due tooversight can cause the cancer to progress to a more advanced stageresulting in decreased patient survivability and increased treatmentcost. This problem is particularly serious when health professionalsattempt to read/interpret breast images quickly. A study on blindre-reading of 427 prior screening x-ray mammograms, which were taken ayear before the cancer detection, published in Radiology (byWarren-Burhenne, et al., 2000, Vol. 215, pages 554-562), reports that asmany as 115 (or 27%) of the cancers could have been detected a yearearlier and should be classed as oversights. In order to reduce theoversight problem, commercial computer-aided diagnosis (“CAD”) systemshave been developed for X-ray mammography screening. Development ofclinically useful x-ray mammography CAD was no trivial matter, as theCAD must achieve sensitivity close to that of human readers. Thedevelopment was undertaken by several commercial firms, some incollaboration with universities and national laboratories, over manyyears, and is believed to have consumed over $100 million in combineddevelopmental cost. The CAD's impact in x-ray mammography is clearlyvisible—after 10 years of its commercial introduction, as reported by astudy published in JACR (by Rao et al., 2010, Vol. 7, pages 802-805), byyear 2008 75% of the screening x-ray mammograms were read with CADassistance.

In the known commercial automated 3D breast ultrasound systems, theultrasound beam is generally directed chestwardly during the scan whilethe breast is generally compressed chestwardly down. This method hassignificant advantages over the earlier non-chestward-compressedultrasound scanning method proposals, such as a method that clamps thebreast between vise-like scanning plates, as in standard x-raymammography. The advantages of chestward scanning include: improvedpatient comfort, lesser depth of breast tissue that needs to be imagedduring the scan, and the possibility of employing higher ultrasoundfrequency resulting in greater image quality. This is discussed in moredetail in U.S. Pat. No. 7,828,733. A composite coronal thick-slicemethod (2-20 mm in slice thickness), which could be used as a guide orroad map to aid the search for abnormalities, is also discussed in U.S.Pat. No. 7,828,733, as is the possibility of a full-breast compositeimage 2502 that preferably is a CAD enhanced expression of thesonographic properties of substantially all of the tissue imaged by thevolumetric ultrasound scans, and of enhancing lesions according to theirlikelihood of malignancy (or another metric of interest). Thethick-slice coronal image has proven helpful as a road map in currentcommercial automated 3D breast ultrasound systems. In commercialsystems, a popular slice thickness of the coronal thick-slice image isbelieved to be 2 mm, which is selected for reasons of good image qualityand less chance to miss smaller lesions or abnormalities. Slicethicknesses down to 0.5 mm also are believed to be used.

In known commercial automated 3D breast ultrasound screening systemsusing chestward compression scans, for each patient, several scans aretypically made on each breast, for example 2-5 scans, although in somecases it can be a single scan and in some cases more than 5 scans. Eachtypical scan generates about 300 new images. Thus, 1,200 to 2,400 ormore new images can be generated for each patient. With the manifold,e.g., 300- to 600-fold increase in the number of new images overscreening x-ray mammography, readers can encounter even more oversightsthan the 27% or so that can be encountered in screening x-raymammography. Thus, there is a need for efficient methods and systems tobetter manage both the reading/interpretation time as well as theoversight problem before breast ultrasound screening can be even morebroadly employed to help more women.

Since the worldwide introduction of automated 3D breast ultrasound usingchestward compression several years ago, radiologists at hundreds offacilities around the world have been struggling to read/interpret thehuge volume of breast ultrasound images per patient study. At thepresent time, it is believed that only the best readers, even using theknown composite 2 mm coronal thick-slice images as road maps, are ablereach the 3 minutes practical goal per patient, while the majority ofthe readers are averaging more than 5 to 8 minutes per patient. Nopublished studies are known on the “oversight” in current commercialautomated 3D breast ultrasound, but one could guess that the oversightrate would not be below that found for screening mammography, i.e., thereported 27%.

The subject matter claimed herein or in a patent issuing from thispatent specification is not limited to embodiments that solve anyparticular disadvantages or that operate only in environments such asthose described above. Rather, this background is only provided toillustrate one exemplary technology area where some embodimentsdescribed herein may be practiced.

All the publications, including patents, cited throughout this patentspecification, are hereby incorporated by reference.

SUMMARY

This patent specification relates to ultrasound examination of patients'breasts in which one or more ultrasound transducers scan a breast toderive measurements of ultrasound response along many planes that extendin chestward directions, the resulting measurements construct a 3Drepresentation of scanned tissue that is enhanced to highlight andcharacterize likely malignancy and is presented and used in ways thatparticularly efficaciously addresses the time goal and the oversightproblems discussed above.

According to some embodiments, an ultrasound transducer scans a breastwith an ultrasound transducer that moves over the breast in a rotary orlinear motion that preferably is automated but can be partly or in somecases mostly or fully manual. The transducer sends ultrasound energyinto the breast and receives ultrasound energy modulated by patient'stissue. The resulting measurements of received ultrasound energy produceraw ultrasound images that typically are in planes transverse to thepatient's chest wall, such as images in axial or sagittal planes.Through processing in specialized computer equipment, these raw imagesare transformed into a 3D representation of scanned tissue, with a valuefor each voxel of tissue in the 3D representation. Computer equipmentuses this 3D representation of scanned tissue to produce ultrasoundimages that conform to planes that are generally parallel to thepatient's chest wall, e.g., images conforming to coronal planes, eachtypically representing a slice of scanned tissue that is 2-20 mm thickin the chestward direction. A typical thickness is 2 mm, althoughthicker or thinner slices can be used.

Specialized computer equipment uses the 3D representation of scannedtissue, or representations derived from it, to facilitate faster andmore reliable discovery of important abnormalities in the scanned tissueand of important characteristics of such abnormalities such as whetherthey are likely malignant or non-malignant. The system thusefficaciously addresses the challenges of rapidly acquiring thenecessary measurements and addressing the issues of a realistic timegoal for assessing the scan results and of reducing oversight errors.

In one example, a system for ultrasound examination of a patient'sbreast comprises an ultrasound transducer compressing an upwardly facingpatient's breast chestwardly down and scanning the breast through agel-impregnated fabric in a scanning motion relative to the breast whilesending ultrasound energy into the breast and receiving ultrasoundenergy from scanned tissue thereby producing ultrasound responses forbreast slices that conform to planes extending down in chestwarddirections; a computer-driven scan controller mechanism and a linkagebetween the controller mechanism and the ultrasound transducer,configured to control the scanning motion of the transducer relative tothe breast; a first programmed computer processor module coupled withthe transducer to receive the ultrasound responses therefrom andconfigured to apply computer processing thereto producing athree-dimensional (3D) structure representing sonographic responsecharacteristics of volume elements (voxels) of scanned tissue; a secondprogrammed computer module configured to apply computer processingalgorithms to the 3D structure to segment out influences of selectedscanned tissue and to find tissue abnormalities in the remainingwhole-breast 3D structure; a third programmed computer module configuredto produce enhancements of at least some of the found tissueabnormalities; a fourth programmed computer module configured to producea whole-breast navigator structure depicting the scanned breast andabnormalities therein that have been enhanced by the third programmedcomputer module; and a computer display configured to produce anddisplay a depiction of the whole-breast navigator structure withabnormalities therein enhanced by the fourth programmed computer module,and respond to user input regarding an abnormality in the whole-breastnavigator structure by producing and concurrently displaying pop-updepictions of the abnormality as it appears in a coronal thick-sliceimage of the scanned tissue that has a selected thickness and in atleast one thin-slice chestwardly oriented image. The scan controllermechanism and the linkage are configured to compress the breast with anessentially planar template rotating relative to the breast and to scanthe breast with the ultrasound transducer in a rotary scan pattern. Thethird programmed computer module is configured to boost representationsof found tissue abnormalities by making likely malignant abnormalitiesdarker or lighter in the navigator structure than if not boosted; toboost representations of abnormalities that represent likelyspeculations in the navigator structure; to boost representations ofabnormalities that represent a likely cyst and enhance an image of acyst in the displayed navigator structure by placing a spot therein thatdiffers from a remainder of the cyst image; and to detect and removeinfluences of ultrasound responses resulting from poor ultrasoundtransducer-to-breast coupling. The fourth programmed computer module isconfigured to produce the whole-breast navigator structure through aprocess comprising assigning to a pixel in a projection of the navigatorstructure a value related to the darkest voxel value in a related columnof voxel values; to produce the whole-breast navigator structure througha process comprising assigning to a pixel in a projection of thenavigator structure a value related to voxel values along a stretch of1-3 mm containing the darkest voxel values of a related column of voxelvalues; and/or to produce the whole-breast navigator structure through aprocess comprising assigning to a pixel in a projection of the navigatorstructure a value related to only some of the voxel values of a relatedcolumn of voxel values.

The detailed description below together with the drawing figurespresents other embodiments and variations.

BRIEF DESCRIPTION OF THE DRAWINGS

To further clarify the above and other advantages and features of thesubject matter of this patent specification, specific examples ofembodiments thereof are illustrated in the appended drawings. It shouldbe appreciated that these drawings depict only illustrative embodiments,and are therefore not to be considered limiting of the scope of thispatent specification or the appended claims. It should also beappreciated that components or steps illustrated in one of the drawingscan be used together with or instead of components or steps illustratedin one or more other drawings within the scope of the disclosedembodiments. The subject matter hereof will be described and explainedwith additional specificity and detail through the use of theaccompanying drawings in which:

FIG. 1A illustrates in a perspective view a full-field automated breastultrasound (FFBU) device.

FIG. 1B illustrates a convention for naming planes relative to apatient's body.

FIG. 2 illustrates in a perspective exploded view an essentially planarscanning template and an ultrasound transducer for scanning achestwardly flattened breast in an automated scan pattern.

FIG. 3A is a top plan view of an essentially planar scanning template;FIG. 3B is a cross-section through lines A-A′, and FIG. 3C is across-section through lines B-B′.

FIG. 4A is a cross-sectional view illustrating a patient's breast thatis chestwardly compressed with an essentially planar template and isbeing scanned with an ultrasound transducer through a radially extendingopening in the template; FIG. 4B is a top view of the template of FIG.4A; and FIG. 4C is a cross-sectional view a scanning template that isotherwise similar to the template of FIGS. 4A and 4B but departs fromabsolute planarity by a departure angle ϕ that is greater than 2.5°.

FIG. 5 is a plan view of a template with a membrane that is permeable toan ultrasound couplant such as a gel, through which an ultrasoundtransducer can scan the breast.

FIG. 6 is a cross-sectional view of the template of FIG. 5.

FIG. 7 is a cross-sectional view similar to FIG. 6 but additionallyillustrating a portion of a breast being scanned and a scanningultrasound transducer.

FIG. 8 is a top view of a template illustrating scan overlap angles.

FIG. 9 is a top view of a template having two radial slots for twoseparate ultrasound transducers, according to some embodiments.

FIG. 10 is a top view of a template that has a non-circular outline andmultiple radial slots through which respective transducers of differentsizes and/or other characteristics scan a breast or at least respectivesectors of a breast.

FIG. 11A illustrates a 3D scanned breast volume with coronal slices,according some embodiments; and FIG. 11B illustrates a display of imagesof such coronal slices.

FIG. 12A illustrates a 3D scanned breast volume and its relationshipwith original 2D scanned slices; FIG. 12B illustrates a display of acoronal slice and associated orthogonal views of original 2D scans; andFIG. 12C illustrates a display of a coronal slice with an abnormalityand of associated orthogonal views that contain the abnormality.

FIG. 13A illustrates a cross-section of breast being scanned with anultrasound transducer that has a curved concave lower side and scansthrough an opening in a template that can be essentially planar orspherical or otherwise curved in two dimensions with a departure anglegreater than 2.5°; and FIGS. 13B and 13C illustrate side views ofultrasound transducers according to some embodiments.

FIG. 14 illustrates in block diagram form a system for acquiring andprocessing ultrasound images and displaying resulting processed imagesin cooperation with a user interface; and FIG. 14A illustrates a displayof images derived from a rotary scan of a breast with equipment such asillustrated in FIG. 1A, including an enhanced whole-breast navigator aidwith an abnormality found therein, and three other images that containthe same abnormality—an original thin-slice chestwardly oriented image,a constructed thin-slice image orthogonal thereto, and a coronalthick-slice image.

FIG. 15 illustrates in perspective a scanning mechanism that uses linearscanning motion rather than the rotary scanning motion of the FIG. 1Aequipment but is otherwise similarly used as a part of an overall breastultrasound system.

FIG. 16 illustrates an ultrasound transducer scanning a breast linearlyalong successive overlapping sweeps.

FIG. 17 illustrates in block diagram form major portions of a breastscanning system.

FIG. 18 illustrates a 3D structure of voxels of a breast, a coronalthick-slice in the structure, and chestwardly directed planes ofthin-slices of the breast.

FIG. 19 illustrates an overall system for ultrasound breast studies,including an example of a display showing a whole-breast navigator aidwith an enhanced representation of an abnormality, several reduced-sizeimages of scans of the breast, and several slice images each containingthe abnormality that can be shown as pop-ups, namely, a thick-slicecoronal image, a thin-slice chestwardsly oriented original scan image,and a constructed thin-slice orthogonal image.

FIG. 20 illustrates computer modules involved in obtaining ultrasoundmeasurements of a breast and producing and using other breastrepresentations, including a whole-breast navigator aid.

FIG. 21A illustrates an example of equipment and methods of producing awhole-breast navigator aid and related pop-ups; and FIG. 21B illustratesanother example of such equipment and methods.

FIG. 22 illustrates a geometry related to producing a 2D representationof a 3D whole-breast navigator aid.

FIGS. 23A and 23B illustrate examples of enhancements of representationsof breast abnormalities.

FIGS. 24A and 24B illustrate other examples of enhancements, includingof representations of masses and speculated abnormalities in a breast.

FIG. 25 illustrates an example of treatment of artifacts resulting froman irregularity in acoustic coupling between an ultrasound transducerand a breast being scanned.

FIG. 26 illustrates an example of computer modules and processesinvolved in acquiring and acting on ultrasound measurements of a breastand producing and using whole-breast navigator aids and pop-ups.

FIG. 27 illustrates and example of computer modules and processesrelated to applying CAD algorithms to filter ultrasound measurements andresults.

FIG. 28 illustrates an example of computer modules and processes relatedto using multi-mode ultrasound measurements to produce an enhancedwhole-breast navigator aid and related pop-ups.

FIG. 29 illustrates another example involving the use of multi-modeultrasound measurements.

DETAILED DESCRIPTION

Several devices and methods of acquiring breast sonographic measurementsare discussed in detail below, then there is a discussion of using thesemeasurements to produce enhanced navigator aids and associated pop-ups.

FIG. 1A illustrates a perspective view of a full-field breast ultrasound(FFBU) scanning apparatus 102 according to a preferred embodiment,comprising a frame 104 that typically contains an ultrasound processor,a movable support arm 106, and a monitor 110 connected to the supportarm 106. FFBU scanning apparatus 102 further comprises an essentiallyplanar radial scanning template 112 and an ultrasound transducer 114.Radial scanning template 112 is configured to chestwardly compress downa breast of a patient (e.g., a supine patient) while rotating around anaxis 122, preferably centered on a nipple hole 204. The ultrasoundtransducer 114 rotates with the radial scanning planar template 112 andscans the breast through a slot-shaped, radially extending openingtherein. Typically, the equipment is provided with severalinterchangeable scanning templates that differ in size and/or shape tofit different patient anatomies and scanning techniques or ultrasoundmodes.

For reference purposes, in this patent specification the +z directionrefers to an outward direction away from the patient's chest, the x-axisrefers to a left-right direction relative to a supine patient, and they-axis refers to a head-to-toe direction. The x-y plane thus correspondsto a coronal plane of a breast, the x-z plane corresponds to an axialplane, and the y-z plane corresponds to a sagittal plane. FIG. 1Billustrates the relevant coronal, axial and sagittal planes. Thisspecification also refers to chestward directions, which include the(−z) direction and more generally directions toward the chestwall of apatient.

Also illustrated in FIG. 1A is a rigid, two-pronged connector 116 and arigid, single-arm connector 120 that mechanically orelectro-mechanically or otherwise connect the radial scanning template112 and the ultrasound transducer 114, respectively, to an actuatorassembly 118 for achieving the movement functionalities describedherein. The elements 116-120 in FIG. 1 are drawn by way of a conceptualexample only and not to scale. In view of the disclosure in this patentspecification, a person skilled in the art would be readily able toconstruct the various mechanical/electrical or other linkages,actuators, motors, sensors, etc., required to achieve the describedmechanical functionalities without undue experimentation. Accordingly,such mechanical/electrical or other details are mostly omitted from thedrawings herein for clarity of description. The actuator assembly 118can be computer-controlled to achieve the required scanning motion oftemplate 112 and transducer 114, and can be referred to as acomputer-driven scan controller mechanism. Connectors 116 and 120 can bereferred to as a linkage or linkage mechanism.

Preferably, support arm 106 is configured and adapted such that theoverall compression/scanning assembly 112-120 (i) is neutrally buoyantin space, or (ii) has a light net downward weight (e.g., 2-3 pounds) forbreast compression, while allowing for easy user manipulation.Optionally, the support arm 106, the template, and/or the transducer(s)can comprise potentiometers and/or other sensors (not shown) to allowforce, position, and/or orientation sensing for the overallcompression/scanning assembly 112-120, the template, and/or thetransducer(s). Other types of force, position, and/or orientationsensing (e.g., gyroscopic, magnetic, optical, radio frequency (RF)) canbe used instead or in addition.

Within frame 104 there can be provided a fully functional ultrasoundengine for driving one or more ultrasound transducers and generatingvolumetric breast ultrasound measurements and images from the scans inconjunction with the associated position and orientation informationregarding transducer 114. The volumetric scan measurements can betransferred to one or more other computer systems for furthercomputer-processing using any of a variety of transfer methods known inthe art. A general purpose computer, which can be implemented on thesame computer equipment set as the ultrasound engine, can be providedfor general user interfacing and system control. The general purposecomputer can be a self-contained stand-alone unit, or can be remotelycontrolled, configured, and/or monitored by a remote station connectedacross a network.

FIGS. 2, 3A, 3B, and 3C illustrate more detailed views of an essentiallyplanar radial scanning template 112 in accordance with an example of adisclosed embodiment. Radial scanning template 112 preferably isrounded, e.g., has a generally circular shape though the shape can berounded without being circular, and defines therein a slot-shapedopening 202 that extends generally radially from a central opening 204.The slot-shaped opening 202 is dimensioned to allow ultrasoundtransducer 114 to scan the breast with ultrasound through opening 202while compressing the breast. Although shown as a one-dimensional arrayin FIG. 2, the ultrasound transducer 114 more generally can bemultiple-arrayed (sometimes referred to as 1.25D, 1.5D, 2D, etc.), orhybridizations thereof without departing from the scope of the disclosedembodiments. In one embodiment, the FFBU scanning apparatus 102 isprovided with an interchangeable (and/or disposable) set of essentiallyplanar radial scanning templates 112 that are differently sized orshaped for differently-sized or shaped breasts. In one example, eight(8) different radial scanning templates having base diameters of 4inches, 5 inches, 6 inches, 7 inches, 8 inches, 9 inches, 10 inches and12 inches are provided. Exemplary diameters for the central opening 204range between about 0.25″ to 1″ (0.25 inches to 1 inch). The slot-shapedopening 202 may have a width typically in the range of 0.25″ to 1″depending on the size of the ultrasound transducer to be used therewith.In addition, a selection of templates can be provided that are notessentially planar but have greater departure angles.

In one example, the ultrasound transducer 114 is supported and/oractuated independently of the radial scanning template 112. In anotherembodiment, the ultrasound transducer 114 is integral with, clipped to,or otherwise secured to or fused with or mounted on the radial scanningtemplate 112 for joint support and/or actuation.

Referring to FIG. 3A, the essentially planar radial scanning template112 is shaped as a circular plate having a circular hole 204 located atthe center of the circular plate 304 and a radially extendingslot-shaped opening 202 from near the hole 204 to near the periphery ofplate 304. FIG. 3B illustrates a sectional view along lines A-A′, andFIG. 3C illustrates a sectional view along lines B-B.

In one example, the radial scanning template 112 is formed of atransparent or at least translucent material having mechanicalproperties similar to those of 40-mil thick polycarbonate plastic,40-mil polystyrene plastic, or a mechanically equivalent thickness ofpolyethylene terephthalate (PETE) plastic. In this embodiment, there issome amount of “give” or flexibility to the template 102, providing somedegree of comfort to the patient as well as adaptability todifferently-sized breasts while at the same time providing forsubstantial stabilization of the breast tissue for reliable volumetricimaging of the breast. Such a template is called “semi-rigid” in thispatent specification. In another embodiment, the material for template102 comprises a transparent or at least translucent material such as140-mil thick glass, 140-mil acrylic, or 140-mil polycarbonate plastic.Such a template is called “rigid” in this patent specification.Preferably, a lower surface of the radial scanning template 112 makes aslippery contact with the skin surface in the presence of an ultrasoundcouplant such as gel between the template and the breast so thatrotation is easily achieved even when the breast is under some degree(e.g., 4-12 lbs.) of downward compression. Despite the slippery contactwith the breast, stabilization is provided by virtue of the generallycircular shape of the radial scanning template 112. Preferably, a curledlip, e.g., as illustrated in FIG. 3B at 304A, is provided around theperiphery 304 as well around the central hole 204 as illustrated at204A, and a similar curled lip is provided at the edges of slot-shapedopening 202 as illustrated in FIG. 3C at 202 a, to prevent skin cuts orchafing and provide additional comfort to the patient, similar to theway curled upper lips are provided on many paper, polystyrene, and PETEplastic drinking cups.

FIG. 4A illustrates a side cut-away view of the essentially planarradial scanning template 112 as it chestwardly compresses down a breast404 having a nipple 406. The view can correspond to the axial orsagittal plane, and also illustrates patient tissue 405 that surroundsbreast 404 laterally (e.g., in the coronal plane). The nipple 406protrudes through the central opening 204. The transducer 114 scans thebreast 404 through the slot-shaped opening 202. FIG. 4B illustrates atop conceptual view of FIG. 4A. FIG. 4C illustrates a template 112A thatcan be otherwise similar to the essentially planar template 112 but hasa conical surface that departs from absolute planarity by a departureangle ϕ (phi) that is greater than 2.5°. Rather than shaped as atruncated cone, template 112A can be shaped as a shallow inverted bowlwith a side curving in two orthogonal dimensions. A template with adeparture angle ϕ greater than 2.5° can be used, if desired, in place ofeach of the essentially planar templates illustrated and discussed inthis patent specification.

Whenever a departure angle is used that moves away from 0°, there is apenalty of scanning through increased breast thicknesses, which ismeasured as the distance from the scan surface to the chest wall. Forexample, if we define t (distance 480 in FIG. 4C) as the maximumdifferential thickness increase from the scan surface to the chest wallsurface, then t could be expresses as the radial length of thetransducer L times the sin ϕ (phi) (the departure angle):t=L sin ϕThe following table shows the relationship:

TABLE 1 L = 3inch L = 4 inch Φ (degree) Sin Φ t (cm) t (cm)  5 0.08720.7 0.9 10 0.1736 1.3 1.8 15 0.2588 2.0 2.6 20 0.3420 2.6 3.5 25 0.42263.2 4.3 30 0.5000 3.8 5.1At 10 MHz, according to D'Astous and Foster (Ultrasound in Med. & Biol.,1986, Vol. 12, pages 795-808), an increase in 2.5 cm in scan depth wouldincrease attenuation by 25 to 50 dB, which could have a serious negativeimpact on image quality. Unless in extraordinary circumstances, eitherdue to breast size or shape, where larger departure angles may need tobe used, for transducers having a radial length smaller than threeinches, one should preferably consider using a departure angle of lessthan 30 degrees. For a three-inch transducer, one should preferably usea departure angle of less than 20 degrees. For a four-inch transducer,one should preferably use a departure angle of less than 15 degrees.

In the particular embodiment of FIGS. 4A and 4B, the slot-shaped opening202 and the ultrasound transducer 114 both extend along substantiallythe entire distance from the central nipple hole 204 to the periphery ofthe radial scanning template such that a complete volumetric scan can beachieved in a single 360-degree rotation, with optional beam-steeringfor facilitating sub-areola imaging. If desired, the rotation angle canbe extended by a few degrees to achieve some overlap of scanned breasttissue and thus ensure complete coverage with no angular gaps.

FIG. 5 illustrates a top view of a radial scanning template 502according to one embodiment, comprising a central opening 504, aslot-shaped opening 506, and a membrane 510 extending across theslot-like opening 506. The ultrasound transducer (not shown in thisfigure) scans the breast through the membrane 510. The membrane 510preferably comprises a fabric material porous to ultrasound couplingagent such as gel, which can be advantageous in that air bubbles arereduced. As used in this patent specification, fabric refers generallyto a material structure of interconnected or interleaved parts, such ascan be formed by knitting, weaving, or felting natural or syntheticfibers, assembling natural or synthetic fibers together into aninterlocking arrangement, fusing thermoplastic fibers, or bondingnatural or synthetic fibers together with a cementing medium, andfurther refers to materials having similar textures or qualities asthose formed thereby, such as animal membranes or other naturallyoccurring substances having fabric-like properties (either inherently orby processing), and such as materials generated by chemical processesyielding fabric-like webbings. One particularly suitable material forthe taut fabric sheet comprises a polyester organza material having afilament diameter of about 40 microns and a filament spacing of about500 microns. However, the fabric membrane may comprise any of a varietyof other fabrics that are substantially inelastic and generally porousto ultrasound couplants without departing from the scope of the presentteachings. Examples include, but are not limited to, polyester chiffonfabrics and cloth fabrics comprising straight weaves of substantiallyinelastic fibers. If the weave is particularly tight, for example, as incloth used in men's dress shirts or in many bed sheets, porosity can beachieved by additional treatment. The additional treatment can involveforming an array of perforations in the cloth or otherwise introducingirregularities that allow the ultrasound couplant to soak or seepthrough.

FIG. 6 illustrates a cross-sectional view of an essentially planarradial scanning template 602 according to one embodiment, comprising acentral opening 604, a slot-shaped opening 606, and a porous fabricmembrane 610 in the form of a stretchable, generally circular fabricsock extending over the entire bottom-side of the planar template 602(i.e., the side that faces and contacts the patient's breast) and acrossthe slot-shaped opening 606 but preferably with a central hole 614 inthe membrane for the nipple to protrude through. The sock can but neednot extend over some or all of the upper side of template 602. Accordingto another embodiment, the porous fabric sock can be mounted on acircular or round frame that is snapped on or otherwise secured to thesubstantially planar radial scanning template 602. The ultrasoundtransducer (not shown in this figure) scans the breast through theporous fabric membrane 610 wetted with an acoustic coupler such as gel.In this example, the template with the fabric sock and the transducerall rotate relative to the breast. As discussed in another examplebelow, an alternative is to compress the breast with a membrane such asgel-wetted fabric, compress the breast through the membrane, and rotatethe template and transducer relative to the breast and the membrane.

FIG. 7 illustrates a side view section of an essentially planar radialscanning template 702 according to a preferred embodiment, comprising acentral opening 704, and a slot-shaped opening 706. The radial scanningtemplate 702 is positioned over a patient (not shown except for aportion of the breast 720) wearing a brassiere-shaped or vest-shapedarticle 710 comprising a porous membrane such as fabric at least overthe breast and preferably with a central hole 714 for the nipple 730 toprotrude through. The ultrasound transducer 114 scans the breast throughthe porous fabric article 710.

FIG. 8 illustrates a top view of a radial scanning template 802according to one embodiment, comprising a single slot-shaped opening 804corresponding to a single ultrasound transducer (not shown in thisfigure). The radial scanning template is preferably rotated 360° plus anoverlap angle α (alpha) during the breast ultrasound scan, the overlapangle (if desired) preferably being in a range of 5° to 45°. The coronalsector associated with the overlap angle alpha (i.e., the pie-shapedsector of the compressed breast subtending the arc between radial lines822 and 824 in FIG. 8) is thus imaged twice. The dual volumetric imagesfor the overlap sector can be advantageously used to reducediscontinuity artifacts in the volumetric representation of the breastthat might otherwise occur along the radial line 822. In one embodiment,the dual volumetric images are arithmetically averaged for smoothingover the discontinuity. However, more advanced stitching techniques canbe used. Other mathematical methods for processing the dual volumetricimages for reducing discontinuity artifacts exist and are within thescope of the preferred embodiments. One non-limiting example is weightedaveraging in which the weights applied to one of the images of theoverlap gradually decrease from unity to zero from the start to the endof the overlap zone while the weights applied to the other image in theoverlap zone gradually increase from zero to unity. For example, theweights applied to the image obtained at the start of the circular scanincrease with angular distance from line 822.

FIG. 9 illustrates a top view of a radial scanning template 902according to one embodiment, comprising two slot-shaped openings 904 and906 corresponding to two ultrasound transducers (not shown) used duringa scan. In one preferred embodiment, the radial scanning template 902 ispreferably rotated by 180° plus, if desired, an overlap angle α duringthe breast ultrasound scan, thereby reducing scanning time as comparedto the use of a single ultrasound transducer. The scan images from thetwo transducers are processed through stitching, blending, or othercompeting algorithms into a volumetric image of the breast.

In another preferred embodiment, the radial scanning template 902 isrotated through the full 360°, plus an overlap angle if desired, withthe different ultrasound transducers being differently configured withrespect to at least one imaging parameter. The resultant volumetricscans are then compounded or composited in any of a variety ofadvantageous ways, with or without different weighing, and/or can beviewed as separate images. Parameters that can be varied among thetransducers include, but are not limited to, scan frequency, tilt angle,elevation beamwidth, scan mode (e.g., B-mode, harmonic, Doppler,elastography), in-plane acoustic interrogation angles, and differentin-plane multi-angle compounding schemes. It should be apparent to aperson of ordinary skill in the art after having read this patentspecification to expand this scan configuration using 2 transducers to ascan configuration using a greater number of transducers.

FIG. 10 illustrates a top view of a radial scanning template 1002according to one embodiment, comprising five slot-shaped openings 1004,1006, 1008, 1010, and 1012 corresponding to five ultrasound transducers(not shown in this figure), each scanning the breast through arespective one of the openings directly or through a membrane (fabric)as described for an individual transducer in other embodiments.According to the preferred embodiment of FIG. 10, at least two of theultrasound transducers have different radial lengths corresponding todifferent distances from the central nipple hole to the periphery of theradial scanning planar template. Each ultrasound transducer scans adifferent coronal sector of the breast. In the example of FIG. 10, whichis for the left breast of a supine patient, the longest ultrasoundtransducer 1006 scans the coronal sector nearest the axilla, while theshortest ultrasound transducer 1012 scans an inferior medial sector ofthe breast. Accordingly, it can be appreciated that the general shape ofa radial scan template according to the disclosed embodiments is notlimited to circular shapes with nipple openings at the geometric center,but rather includes different shapes and different locations of thenipple opening relative to the template's radial periphery. Likewise, aradial scan template according to the preferred embodiments is notlimited to a circular shape, but rather can have a differently shapedperiphery (e.g., oblong, elliptical, cam-shaped).

The obtained ultrasound scans can be advantageously used in a variety ofways in accordance with the disclosed embodiments. For example, it hasbeen found that the acquired volumetric measurements are particularlyadvantageous for generating coronal slice images of the breast as shownin FIG. 11A, each preferably representing a slice that has a selectedthickness in the z-direction (i.e., a direction away from the patient'schest wall), although images of slices that have other orientations andmay differ in thickness from each other also are with the scope of thispatent specification. The slice thickness preferably is in the range of0.5-2.0 mm, but can be in the range of 0.1-1.5 mm, or 0.1-2.0 mm, or0.1-10.0 mm, and even a greater range. Another advantage of displayingcoronal images is that they can show lesion spiculations well, which area readily recognizable feature of a cancerous lesion.

FIGS. 11A and 11B illustrate a 3D image 1101 of the breast representedas slices 1110-1120 reconstructed from 2D radial scan images such asimage 1106, and the display of slice images 1110-1120 of slices of the3D structure of breast voxel values. The 3D structure 1101 isreconstructed from a great number of original 2D images from the radialscan that are transverse to the coronal plane, e.g., they extend inchestward directions. One such original 2D image 1106 is shown. Alsoshown is the central nipple hole 1104. The 3D image 1101 can beconsidered as divided into images of coronal slices of the breast(slices perpendicular to the z-axis) 1110, 1112, 1114, 1116, 1118, 1120,etc., reconstructed from the volumetric stack 1101 as known theultrasound imaging technology. FIG. 11B illustrates an example of howthe slice images can be displayed to the physician or other healthprofessional. The last (bottom) slice 1120 is usually the slice at thechest wall or rib cage (which generally would show ribs 1122, 1123,1124, etc. to confirm that adequate breast penetration has beenachieved). The nipple and sub-areola regions, obtained either throughbeam-steering or manual scanning with a handheld transducer orotherwise, can be displayed in stitched images or separately.

FIGS. 12A and 12B illustrate a single corona thick-slice slice image1210 in a volumetric 3D image or stack 1201 of breast tissue, andthin-slice 2D images. Two original 2D radial scan images 1206 and 1208bisect the 3D image, for example in a sagittal plane, and are spaced180° from each other. Alternatively, the 2D radial scan thin-sliceimages can be at other chestward orientations. The central nipple hole1204 is also shown. FIG. 12B illustrates a display of 2D images 1206 and1208 together with a display of 2D images 1236 and 1238 that are a pairorthogonal to the pair 1206 and 1208 (e.g., if the pair 1206-1208 aresagittal images than the pair 1236-1238 are axial images). Chest wallline 1209 is also shown.

Notably, in this example the two orthogonal pairs of images are original2D radial scan images, unlike similar pairs in known commerciallyavailable FFBUs, where orthogonal pairs are believed to be constructedfrom a volumetric reconstructed 3D image stack and consequently havereduced image quality. Coronal thick-slice images as shown in FIG. 11Bcan be reviewed quickly, and/or a cine or other review of the coronalimage in FIG. 12B can be carried out, and/or a quick cine or otherreview of the original 2D images in FIG. 12B. One way to perform a cinereview of the original 2D images is simply to rotate the coronal slice1210 to view the 180° pairs. Rotation of the coronal slice can be donewith a control knob, by a cine review control, or by another interface,while other information such as the rotational angle, left or rightbreast, patient position, etc. are also displayed (not shown in FIG.12B).

An abnormality may be noted in a displayed coronal thick-slice of thepatient's breast. As illustrated in FIG. 12C, when an abnormality 1250in the coronal slice is found, with a click on the abnormality 1250 witha mouse or controller or by some other input, corresponding abnormality1251 in the original 2D radial scan thin-slice image or imagescontaining this abnormality can then be automatically pulled up anddisplayed through suitable algorithms programmed in frame 104 as knownin ultrasound image processing technology. Similarly, a constructed 2Dimage 1240, orthogonal to view 1208, containing this abnormality 1252can also be shown simultaneously. Also visible in constructed image 1240is chestwall 1241.

FIG. 13A illustrates the use of an ultrasound transducer 1314 that has aconcavely curved bottom 1314A facing and compressing and scanning apatient's breast 1304 that is compressed with a rotating, concavelyshaped template 1312 having a central opening through which the nipple1305 protrudes. While template 1312 is illustrated as compoundlyconcavely curved, it can be planar or spherical in shape, and transducer1314 can still have a similar concavely curved lower side 1314A, or itcan have a generally planar lower side. In embodiments where severaltransducers concurrently scan a breast, e.g., as in FIG. 10, eachtransducer can have a concave lower side or some of the transducers(e.g., the shortest transducer(s)) can have straight lower sides, or allcan have straight lower sides. In cases where the template 1312 isconcave such as shown in FIG. 13A, the departure angle ϕ can be greaterthan 2.5°, but preferably would not exceed about 20° as shown. FIG. 13Billustrates a side view of transducer 1314 having a curved lower side1314A in a radial plane, but a straight lateral lower side. FIG. 13Cillustrates a side view of a multi-array transducer 1314C, according tosome embodiments. The multi-array transducer 1314C is wider as shown.Additionally, the lower curved side 1314 d can be concavely curved bothin the radial and in the lateral dimensions to match a concavely curvedtemplate 1312.

FIG. 14 illustrates in block-diagram form certain computer-implementedfacilities for carrying out scanning and image processing and displayaccording to embodiments described above. One or more ultrasoundtransducers 1402 scanning the breast as described above supply raw 2Dultrasound images to a pre-processing facility 1404 that applies variousalgorithms to the raw images as known in the pertinent technology togenerate pre-processed 2D thin-slice images each representing a planarsection of the breast conforming to a plane extending in the chestwarddirection (transverse to the coronal plane). These pre-processed 2Dimages are supplied to a facility 1406 that reconstructs from them a 3Dstructure of voxel values of the breast and, if the 3D image is in aform different from a stack of coronal slice images representing breastslices of selected thicknesses (e.g., as a non-limiting example, slicesthat are 0.5-10 mm thick) the facility generates such slice images fromthe 3D image of the breast. Thus far, the operation is similar to theknown generation of 2D and 3D images and slice images in commerciallyavailable FFBU devices, except that the raw 2D thin-slice can all beoriginal scan images rather than thin-slice images reconstructed fromthe 3D representation of voxel values, which reconstructed images maynot be as true as the actual original scan image. A display facility1408 receives the pre-processed 2D images from facility 1404 and the 3Dimage and/or the coronal slice images from reconstruction facility 1406.The display facility 1408 includes one or more computer display screensand computerized processing circuits and software, and operates underthe control of a user interface 1410 to generate and display sliceimages such as 1110 through 1120 as illustrated in FIGS. 11A and 11Band/or a slice image such as 1210 together with pairs of pre-processed2D images such as 1206-1208 and 1236-1238 illustrated in FIGS. 12A and12B. The coronal slice images of FIG. 11B can be displayed concurrentlyor in sequence or in a cine mode. Per operator control through interface1410, the images can be moved on the display screen or superimposed orone or more can be changed, such as by changing the orientation of theslice that the image represents, or the thickness of the slice, or thetransparency of one or more superimposed images, or the type ofprojection that generated the slice (e.g., minimum or maximum intensityprojection) by applying image processing techniques known in theultrasound imaging field and/or in other image processing and displayfields such as post-production of still or video images. Similarly, theimages illustrated in FIG. 12B can be displayed in the illustratedformat or in other formats known in the pertinent technology. Asnon-limiting examples, the slice image 1210 of FIG. 12B can be changedto represent a slice that has a different orientation or thickness or toan image of the slice that was generated in a different way (e.g., by adifferent type of projection), and the 2D images or FIG. 12B also can bevaried under control of inputs from interface 1410, such as by rotatingtheir planes around an axis normal or only transverse to the coronalplane, by changing the angle between the planes of the two pairs of the2D images, by changing the range of pixel values in the images (i.e., bycontrolling the window width of the images), and in other ways known inthe technology of displaying pixel value images. Some or all of thefacilities illustrated in FIG. 14 can be implemented by programming thecomputing equipment in frame 104 or FIG. 1A, or by carrying outprocessing in separate computer equipment connected thereto, or in aworkstation that is remote from frame 104 but is coupled therewith toreceive the 2D images that the transducer(s) generate. The softwarecontrolling the operation of the equipment illustrated in FIGS. 1A and14 can be stored in non-transitory form in computer-readable media toform a program product.

According to some embodiments, images from prior examinations can beshown together with images of the current examination of a patient usingdisplay facility 1408 to view changes over time. According to someembodiments, an image that represents differences over time between theimages is displayed using display facility 1408. According to yet otherembodiments, CAD (computer aided detection) results and/or other imageenhancing results can also be displayed using display facility 1408.

FIG. 14A illustrates an example of a display resulting from a rotaryscan of a breast and processing of the resulting measurements asdescribed in the several examples of such processing in this patentspecification, and includes at lower right a whole-breast navigator orguide image or aid 1450 that highlights and enhances a representation ofa suspicious lesion indicative of a likely abnormality. The displayincludes at lower left an image of a coronal thick-slice that forexample can be in the indicated range of thickness, and includes aboveand to the right of the coronal slice image two thin-slice images. Forexample, one of the thin slice images can be an original 2D scan imageand the other can be a constructed thin-slice image of breast anatomy ina plane orthogonal to that of the original thin-slice image. The coronalthick-slice image and each of the thin-slice images can be automaticallyselected to include the abnormality, for example in response to a userpointing to the abnormality in the whole-breast navigator or guide imageor aid or in response to some other action or event.

In one example, a display such as in FIG. 14A includes only the originalscan thin-slice image shown concurrently with the whole-breast navigatoraid and the thick-slice coronal image, without the constructed 2Dorthogonal image seen in FIG. 14A. Preferably, the thin-slice image isan original 2D image derived from scanning the breast with an ultrasoundtransducer. As noted, the thin-slice original image and the thick-sliceconstructed coronal image are automatically selected, based on the 3Dstructure of voxels of the breast and the enhanced navigator aid tocontain an abnormality that a used points to in the navigator image, forexample by hovering a pointer over the abnormality in the navigator aid.If the whole-breast navigator aid contains only a single abnormality,the pop-ups can appear without prompting by the user. Or, a protocol canbe included in the system to automatically produce relevant pop-ups foran abnormality next to one that the user has just viewed and considered,with or without prompting by the user.

Skilled persons would appreciate that any of a variety of differentframe assemblies can be used that position, compress against the breast,rotate, and otherwise manipulate the scanning template, whether thescanning template is permanently used and re-used for different patientsor is disposable for each patient, without departing from the scope ofthe present teachings. Moreover, in one or more alternative preferredembodiments, the basic profile of the radial scanning template can beelliptically shaped, etc., rather than strictly circular-shaped asindicated in some of the attached drawings. The scanning surface of theultrasound transducer can be arched or otherwise made to conform toanother curved surface in a similar manner, if desired. Therefore,references to the details of the embodiments are not intended to limittheir scope.

FIG. 15 illustrates a scanning pod 1502 that scans a chestwardlycompressed breast with an ultrasound transducer 1504 in a generallylinear pattern rather that in a rotary pattern as in FIG. 1A, andproduces chestwardly oriented 2D original slice images from which a 3Dstructure of breast voxel values can be constructed. The scanning pod1502 can be attached to an articulated arm 1506 similar to arm 106 ofFIG. 1, and can be associated in a similar manner with a processor framesuch as frame 104 of FIG. 1. Pod 1502 can be similar or even the same asused in a commercially available system currently offered commerciallyin the U.S. by GE Healthcare under the trade name ABUS and previouslyavailable from U-Systems, Inc. of California. Such a system is discussedin U.S. Pat. Nos. 7,828,733 and 8,496,586. As in the commerciallyavailable system, scanning pod 1502 can be brought down to chestwardlycompress an upwardly facing breast of a patient 102 resting on a tablein a position such as the supine position. Pod 1502 includes transducer1504 that is driven mechanically, electromechanically or otherwise toscan the compressed breast through a coupling medium and send ultrasoundenergy into the breast and receive a sonographic response whilecompressing the breast portion that it contacts through the couplingmedium. A computer-driven scan control mechanism 1508 drives thetransducer or at least controls some aspects of the scanning movement,through a linkage mechanism 1510. Transducer 1502 scans a compressedbreast schematically indicated at 1512 in a single sweep or swath ormore typically in several partly overlapping swaths as is known in thecommercial system, through a coupling medium such as a gel-wetted fabricbetween the bottom surface of pod 1502 and the breast.

FIG. 16 illustrates yet another way to obtain chestwardly oriented 2Doriginal slice images. An ultrasound transducer 1602 scans a chestwardlycompressed breast 1606 along a succession of partly overlapping sweeps,swaths, or scan rows 1604 that are generally linear to thereby cover theentire breast. The 2D images from the respective swaths can be stitchedinto a 3D structure representing the breast, with appropriate blendingof the overlapping portions. Transducer 1602 is supported by a linkage(not shown) similar to linkage 118 of FIG. 1A and linkage 1510 of FIG.15 and can be driven by a device similar to computer-driven scancontrollers 118 of FIG. 1A and 1508 of FIG. 15 but configured to drivethe transduced along swaths 1604. The scanning arrangement can besimilar to or even the same as that used in an ultrasound breastscanning system offered by Sono-Cine of Reno, Nev. under the trade nameAWBUS. The system includes a known ultrasound processing engine (notshown) to produce images for display from the sonographic responsecollected by transducer 1602.

FIG. 17 illustrates in block diagram form an overall arrangement ofequipment that can use the rotary scan of FIG. 1A, the generally linearscan of FIG. 15, and/or the narrower swaths scan of FIG. 16, oralternative scanning patterns. Scanning pod 1702 and control unit 1704,which include an ultrasound transducer and any needed computer-drivenscan controller mechanism and linkage mechanism, cooperate to scan achestwardly compressed breast and produce a sonographic response thattypically is in the form of 2D chestwardly oriented thin-slice images.Control unit 1704 uses the 2D thin-slice images to produce a 3Dstructure of the scanned tissue voxel values. Further operations incontrol unit 1704 and/or in workstation 1706 produce thick-slice imagesof the sonographic response that typically conform to coronal planes butif desired can conform to other planes or even to curved surfaces, andenhanced whole-breast navigator aids and region of interest (ROI) imagesthat can be displayed at workstation 1706 and/or at a display 1708 thatcan be on a common support with pod 1702. Patient 1710 is on a table1712, generally in a supine position but can be in other positions solong as the breast being examined faces generally up and is compressedby pod 1702 generally chestwardly down. The connection between controlunit 1704 and workstation 1706 can be wired or wireless, directly orindirectly such as through a hospital's PACS facilities. According tosome embodiments, information can be accessed from a server via astandard protocol such as DICOM. Further details of the basic system canbe found in the cited patents or in information regarding thecommercially available system but are not included here for the sake ofconciseness. The system is modified to process the sonography responseas described below, using the computing facilities of engine 106 and/orworkstation 110 through the operation of algorithmic software, firmware,and/or hardware to carry out processing described below.

FIG. 18 illustrates aspects of chestward compression scan orientationsin relationship to a 2D coronal thick-slice of a patient's breast, aswell as a volume from which an enhanced, whole-breast navigator overviewimage can be produced, according to some embodiments. Shown are a 2Dcoronal thick-slice guide (k,l,m,n), and the volume (a,b,c,d,e,f,g,h)from which the enhanced, whole-breast navigator overview image can beproduced. Chestwall 200 is also shown. The planes a,b,c,d to e,f,g,h areoriginal axial thin-slice scanned images. The z-direction in FIG. 18 isa chestward direction, and the axial images are in planes that areperpendicular to the length of the patient.

In this patent specification, the original chestwardly oriented scanimages are referred to as thin-slice images because each represents avery thin slice of tissue, such as 0.1 mm or even less. The termthick-slice image refers to an image that typically represents a tissueslice that is 0.5-20 mm thick, although variations are possible. Theterm whole-breast navigator overview image or aid refers to an imagethat represents a 3D volume of tissue that typically is the entirevolume of interest that generates the sonographic response, such as allthe scanned breast tissue after segmenting out tissue that is not ofinterest such as ribs and muscle, or represents at least tissue of muchgreater thickness than a thick-slice. The sonographic response contentthat is segmented out typically includes responses from tissue such asthe patient's ribs, chest wall (pectoral muscle(s) and connectivetissue), and/or skin plus possibly a layer of breast tissue close to theskin. The term user in this patent specification refers to the personwho operates the system to generate the sonographic response from whichthe images are derived and/or a person who views or otherwise utilizesthe images to screen and/or diagnose a breast or a patient.

In overview, in the disclosed embodiments one or more ultrasoundtransducers transmit ultrasound energy into a patient's breast andreceive sonographic responses that are converted through processing incomputer circuits into a three-dimensional (3D) structure representingtissue producing the responses, which 3D structure thereafter isenhanced by removing influences of non-breast tissue that is not ofinterest. The so-enhanced 3D structure is acted on to produce one ormore enhanced, whole-breast navigator overview images or aids andpop-ups that are uniquely configured to speed up the screening anddiagnosis of the patient's breast and to reduce occurrences of missedlesions. The navigator overview images or aids can be further configuredto include indications, such as computer-aided detection (CAD) marks orenhancements that rely mainly on other processes and can identify assuch both likely malignant and likely benign abnormalities found in thebreast and enhance the representation of certain aspects ofabnormalities, and can be displayed together with other images that canhelp further characterize the abnormalities.

FIG. 19 illustrates examples of images produced and displayed inaccordance with disclosed embodiments. A computer screen 1902 displaysan interactive user interface including on the right a 2D representationof a 3D enhanced, whole-breast navigator overview image or aid 1904 thatincludes a representation of an abnormality 1905. Image 1904 isgraphically altered to provide improved navigation pertaining to thecharacteristics of the lesion features to the user/physician as to whichlesion(s) can or should be given priority for interpretation. Forexample, it can be marked to identify the abnormality 1905 as benign ormalignant. Display screen 1902 in this example further includes at upperleft reduced size and resolution versions 1914 of all or at leastseveral of the whole-breast navigator overview images of the individual3D scans of both breasts of the patient. In this example, three 3Dvolumetric scans are made on each breast of the patient. The reducedresolution version 1914 includes the currently viewed image 1914A isdisplayed in higher resolution and larger size as enhanced, whole-breastnavigator overview image 1904. A spiculated lesion 1905, which has ahigh probability of being a cancer, is shown in a coronal thick-sliceview 1916 that can be automatically selected to include the abnormality1905 seen in the navigator aid 1904. Corresponding views in the original2D original thin-slice scan image 1918 and a constructed orthogonal 2Dthin-slice image 1920 also can be automatically selected to show thesame abnormality 1905, which in this case exhibits characteristics ofhigh probability of being a cancer. This automatic selection can be inresponse to a user pointing to lesion 1905, for example with a userinterface device, or even without pointing if there is only oneabnormality shown in navigator aid 1904. The whole-breast navigatorimage 1904 can be altered such that the spicules of the spiculatedlesion 1905 can be seen prominently therein. This added informationallows the user/physician to pay immediate attention to this feature.

The display of FIG. 19 can be set to show various protocols. Onepreferred example is a set of the 2D representation of the enhanced 3Dnavigator image, a 2D representation of a constructed thick-slicecoronal image that includes a representation of a selected abnormalityseen in the navigator aid, and an original 2D thin-slice image thatincludes the same abnormality and possibly the reduced-size images seenat upper left (but without the constructed orthogonal thin-slice image).Another protocol may put on the display the same or similar set ofimages of both breasts of a patient, or images from studies of the samebreast or breasts taken at different times. The display is interactiveso that a user can scroll through thin-slice images adjacent in space tothe one that automatically pops us when a user points to an abnormalityin the navigator aid, and through thick-slice images adjacent to theautomatically displayed version.

In FIG. 19, a user interface/workstation 1906 includes display 1902,input devices such as keyboard 1908 and mouse 1910, and a processingsystem 1912. Other user input methods such as touch sensitive screenscan be used. User interface/workstation 1902 can be unit 104 of FIG. 1A,or units 1404 and 1406 of FIG. 14, or 1704 and 1706 of FIG. 17.Processing system 1912 can be a suitable personal computer or aworkstation that includes one or more processing units or modules 1912A,input/output devices such as CD and/or DVD drives, internal storage1912B such as RAM, PROM, EPROM, and magnetic tape storage media such asone or more hard disks for storing the medical images and relateddatabases and other information, as well as graphics processors suitableto power the graphics being displayed on display 1902.

In one example, processing system 1912 comprises a first programmedcomputer processor module coupled with the ultrasound transducer of FIG.1A, 15 or 16 to receive the ultrasound responses therefrom andconfigured to apply computer processing thereto producing athree-dimensional (3D) structure representing sonographic responsecharacteristics of volume elements (voxels) of scanned tissue, a secondprogrammed computer module configured segment out influences of scannedtissue that is not of interest and to apply computer processing to theresulting 3D structure to find therein tissue abnormalities, a thirdprogrammed computer module configured to produce enhancements of atleast some of the found tissue abnormalities, a fourth programmedcomputer module configured to produce a navigator aid structuredepicting the entire scanned breast tissue of interest and theabnormalities therein that have been enhanced by the third programmedcomputer module, and a computer display configured to produce anddisplay a depiction of the navigator structure with the abnormalitiestherein enhanced by the fourth programmed computer module and to respondto user input regarding an abnormality in the navigator structure byproducing and concurrently displaying pop-up depictions of theabnormality as it appears in a coronal slice of the scanned tissue thathas a selected thickness and in one or more thin-slice images thatconform to chestwardly directed planes.

In contrast to using a coronal thick-slice image as a “guide image” asin conventional approaches, the user interface/workstation 1912 producesand uses a whole-breast navigator overview image 1904 that combinesinformation from the whole 3-D structure of breast tissue of interest.Also in contrast to conventional thick-slice or even possibleentire-breast images, the entire-breast navigator overview imagesdescribed in this patent specification are enhanced by segmenting outinfluences of non-breast tissue that can hide or obscure importantabnormalities, and can include enhanced depictions of abnormalities tohighlight or suppress features thereof and to highlight specifiedabnormalities and characteristics thereof.

FIG. 20 is a flow chart illustrating aspects of one example of producingand displaying an enhanced, whole-breast navigator overview image. Instep 2010, a first programmed computer module constructs a 3D structureof a breast, for example by carrying a rotary or a linear scan of abreast as described above and constructing the 3D structure from thechestwardly oriented thin-slice images of sonographic response.Typically, Cartesian coordinates are used in processing the scanmeasurements and constructing the thin-slice and thick-slice images, the3D structures of voxel values, and the enhanced navigator image. Inrotary scanning as illustrated in FIG. 1A, the position of a point onthe ultrasound transducer can be tracked in terms of its distance R fromthe center of rotation and the current angle α (alpha) from a startingangle. The conversion to Cartesian coordinates is well known—thex-coordinate of the point and the column of breast voxels under thepoint is x=R cos α and y=R sin α. In this manner, the illustratedcomputer modules can convert the rotary coordinates R,α to the requiredCartesian coordinates for further processing. In step 1214, a secondprogrammed computer module segments breast tissue, for example byremoving influence of ribs and/or other non-breast tissue and skin andpossibly a layer close to the skin, and in step 2016 filters theresulting breast 3D structure, for example by computer-aided detectionalgorithms and/or other computer-processing operations, to find andpossibly characterize suspected abnormalities. The skin region and alayer underneath can be simply defined as the region within a certaindistance range from the top or from the scanning ultrasound transducer,say 0 to 2 mm. The filters applied in step 2016 can be a gradientconversion filter configured to enhance dark rounded shapes thatresemble masses in the breast and a line conversion filter configured toenhance lines radiating from a center that resemble a spiculation orarchitectural distortion in the breast. The filters can include acomputer aided detection (CAD) algorithm 2020 that detects and ranks thelesions by likelihood of being actual lesions and/or by likelihood ofmalignancy. Other filters 2022 can be derived from techniques such asminimum voxel value, Doppler data, and/or elastography data. In step2018, a third programmed computer module applies computer processing tothe results of step 2016 to enhance at least some of the foundabnormalities, for example by feature weighted compounding. According tosome embodiments, weights, w(x,y,z) for compounding are generated bycombining the outputs of the filters:w(x,y,z)=Σ_(i) ^(k) k _(i) f _(i)(x,y,z)where N is the total number of filters, f_(i) (x,y,z) is the output ofi-th filter and k, is a constant scaling factor for i-th filter. Theweight is also normalized from 0 to 1 as the probability of a voxeloverlap with a malignant lesion.

In step 2024, a fourth programmed computer module constructs anddisplays an enhanced, whole-breast navigator overview image a(x,y) byprojecting the 3D structure produced in step 2018 along the z direction(preferably excluding some or all of skin and underlying thin layer,chestwall and rib regions) modulated by the weight. The relationshipbelow is one example of the projection by taking the minimum value ofthe weighted intensity alone the z-axis.a(x,y)=MIN_(across z)(I(X,y,z)(1−w(x,y,z))where I(x,y,z) is the intensity or voxel value of the 3D ultrasoundstructure.

FIG. 21A illustrates in more detail certain aspects of producing anenhanced, whole-breast navigator overview image based on a 3-D structureof a breast using CAD, according to some embodiments. Blocks 2010, 2012,and 2014 represent programmed computer modules similar or identical tothose shown and described with respect to FIG. 20. In block 2110, aprogrammed computer module applies CAD algorithms to find regions ofinterest (ROIs) containing likely abnormalities. For diagnosticprocedures, users/physicians have been using 2D ultrasound todistinguish and classify breast lesions. For example, see the study byStavros et al. in 1995 Radiology, Vol. 196, pages 123-134, entitled:“Solid breast nodules: Use of sonography to distinguish between benignand malignant lesions”. CAD algorithms have been developed todistinguish between benign and malignant lesions in 2D and 3D images.For example, see (a) the study by Drukker et al. in 2002 MedicalPhysics, Vol. 29, pages 1438-1446, entitled: “Computerized lesiondetection on breast ultrasound”; and (b) the study by Tan et al. in 2012IEEE Trans. on Med. Imaging, Vol. 31, pages 1034-1042, entitled:“Computer-aided lesion diagnosis in automated 3D breast ultrasound usingcoronal spiculation”. For screening purposes, most, if not all, of theprior CAD developments have been concentrated on detecting malignantlesions. However, according to some embodiments in block 2110, a CADalgorithm can be used to detect likely malignant lesions as well aslikely benign lesions. A primary reason for detecting benign lesions andmarking them in 3D volumetric ultrasound is to lower the distraction bythese likely benign lesions during the interpretation byusers/physicians in screening procedures. For further examples of CADand computer-aided classification, see, e.g. Karen Drukker, et. al.,“Computerized Detection Of Breast Cancer On Automated Breast UltrasoundImaging Of Women With Dense Breasts,” Med. Phys. 41 (1), pp. 012901-1-9,January 2014; Tao Tan, et. al., “Computer-aided Detection of Cancer inAutomated 3D Breast Ultrasound,” IEEE Transactions On Medical Imaging,Vol. 32, No. 9, September 2013, pp. 1698-1706; Tao Tan, et. al.,“Computer-Aided Lesion Diagnosis in Automated 3-D Breast UltrasoundUsing Coronal Spiculation,” IEEE Transactions On Medical Imaging, Vol.31, No. 5, pp. 1034-1042, May 2012; and Woo Kyung Moon, et. al.,“Computer-Aided Classification Of Breast Masses Using Speckle FeaturesOf Automated Breast Ultrasound Images,” Med. Phys. 39 (10), pp.6465-6473, October 2012. One of more of the CAD algorithms in the citedpublications can be used in step 2110, by suitably configuringultrasound engine 104, 1406, 1704, 1706, and/or 1812 by software,firmware, and/or hardware, as can be appreciated by persons skilled inthe technology.

Following CAD detection of ROIs in block 2110, according to someembodiments the ROIs are darkened in block 2112, for example by scalingeach voxel value within each ROI according to the likelihood ofmalignancy as determined by the CAD process in block 2110. In oneexample, all voxels within an ROI having a 70% chance of malignancy asdetermined by the CAD algorithm, are multiplied by 0.3 (where1=likelihood of malignancy) which will darken the pertinent voxel valuesin the ROI. According to other embodiments, other methods ofROI-weighted voxel darkening can be used.

According to other examples, in block 2112, the ultrasound 3D structureof voxel values is split into low and high frequency components, and avolume structure is produced that is a weighted combination of thelow-pass (background) and high-pass (signal) components. According tosome embodiments, this is accomplished by producing a background volumewith any of a number of known techniques (including nonlinear smoothing,in which case the background image isn't strictly “low-pass” in thetraditional sense) and deriving the signal volume as the differencebetween the original and the background. The simple summation of thesederived background and signal volumes can reproduce the original 3Dstructure faithfully. Over most of the 3D volume, the two components aresummed with equal weight, i.e., in a simple summation, but in theneighborhood of a CAD-found ROI of a likely abnormality, the signalcomponent is weighted more heavily, emphasizing image detail in thatvolume.

After each CAD-found ROI is darkened in block 2112, a suitable method isused to select the appropriate pixel values for a 2-D representation ofthe 3D navigator aid structure, such that the user's attention can bedrawn to the appropriate features from the 3-D image data.

According to some embodiments, one or more graphical alterationtechniques are used to further enhance the usability of the resultingnavigator aid. Examples of such techniques include posterior enhancement2130, edge enhancement 2132, line detection/enhancement 2134, and poorcoupling artifact detection 2136. The techniques applied in computermodules 2130, 2132, 1734, and 2136 generate new 2D images 1740, 1742,1744, and 2146 respectively. Posterior enhancement block 2130, accordingto some embodiments, adds pixel values from an area below a detectedROI, which tends to make malignant lesions darker in the center, butmake benign cysts lighter in the center. In block 2132, according tosome embodiments, a high pass filter is used to enhance edges of ROIs.In some examples, the negative values of voxels of pixels are clipped tozero and then the filtered results are added back to the image. In block2134, according to some embodiments, a line detection/enhancementtechnique is carried out in a volume of voxels including and above adetected lesion. Techniques 2130, 2132, and 2134 are described infurther detail in FIGS. 23A, 23B, 24A and 24B, infra. In block 2136, atechnique is used to detect artifacts resulting from locally pooracoustic coupling. Some or all of the individual 2-D coronal images2120, 1721, 2142, 2144, and 2146 are summed together at 2150. Accordingto some embodiments, equal weighting can be used, but it has been foundthat in many cases a varying weighting algorithm can be more effectivein generating a highly useable enhanced, whole-breast navigator overviewimage. In many cases it has been found that the 2-D coronal image 2120is more heavily weighted, although the individual weights depends onwhich projection method (e.g. 2114, 2116, or 2118) and what types ofgraphical detection/enhancement techniques (e.g. 2130, 2132, 2134, and2136) are used. The 2D coronal images 2120, 2140, 2142, 2144, and 2146can be intermediate versions of the enhanced, whole-breast navigatoroverview image. Alternatively, they can be successive thick-slice imagesthat are combined at 2160 into an enhanced, whole-breast navigatoroverview image.

FIG. 21B illustrates aspects of producing an enhanced, whole-breastnavigator overview image based on 3-D image data without using CAD,according to some embodiments. FIG. 21B is similar or identical to FIG.21A in many respects so comparable equipment is similarly numbered, butcan be used to produce a suitable enhanced, whole-breast navigatoroverview image 2160 without the use of a CAD algorithm. In FIG. 21B, theskin, chest wall, and ribs are detected and segmented in blocks 2012 and2114. One of the projection techniques 2114, 2116, or 2118 is then usedto generate image 2120. According to some embodiments, image 2120 may besuitable for use as an enhanced, whole-breast navigator overview image2160 without further alteration. According to some other embodiments,edge enhancement and line detection/enhancement algorithms 2130 and 2134can be applied to the entire segmented 3-D image (rather than just toselected volumes based on a CAD-found ROIs). According to someembodiments, the coupling artifact detection technique 2136 can be used.The resulting 2-D images are then summed together at 2150 using suitableweighting to generate the final enhanced, whole-breast navigatoroverview image 2160. As in the process of FIG. 21A, an alternative is toprocess several thick-slice images in the indicated manner and thencombine then into the desired enhanced, whole-breast navigator overviewimage in step 2160.

FIG. 22 is a diagram illustrating aspects of assigning 2D pixel valuesbased on 3D voxel column characteristics, according to some embodiments.In FIG. 22, the 3D segmented volume 2200 is depicted. One voxel column2210 is shown. According to some embodiments, the 2D pixel value for the2D combined or compounded image can be selected by assigning it to theminimum value found in the voxel column. This option is shown in block2116 of FIG. 21A. However, it has been found that such an approach inmany cases leads to an overly noisy 2D image that is not as useful infacilitating the user's efficient screening. It has been found thatbetter results can often be obtained by assigning the pixel in the 2Dimage to a value that is not the lowest (darkest) in the voxel column.In block 2114, the voxel column is searched for the darkest contiguouslength of a specified extent, such as 2 mm, and the 2D pixel value isassigned to an averaged value of those contiguous voxels. Other lengthsbesides 2 mm can be used depending on the situation. According to someother embodiments, the 2D pixel value is assigned to a value at which 4percent of the voxels in the column have lower (darker) values. Otheramounts besides 4 percent can be used also, depending on the situation.According to some other embodiments, some other method of assigning 2Dpixel value is used based on the voxel values. Following a suitableprojection method (e.g. 2114, 2116, 2118 or some other method), a 2-Dimage 2120 is generated.

FIGS. 23A and 23B are transverse and coronal views, respectively,illustrating CAD ROI alteration techniques for use in enhanced,whole-breast navigator overview images, according to some embodiments.According to some embodiments, a line enhancement, such as secondderivative of voxel filter is applied to voxels inside a sub-volume,shown as Zone 2320. The line enhancement filter is a 2D filter in thecoronal plane, i.e. approximately parallel to the chest wall, where thespiculation is most prominent. The size of the sub-volume 2320 in thecoronal plane is proportional to, but larger than, the size of the CADROI 2302 in the coronal plane. The location of the sub-volume 2320 alsoincludes a region above the CAD-found ROI 2302 as seen in FIG. 23A,since this is also where spiculation is likely to be most prominent. A2D sub-image is generated by the average voxel value of theline-enhanced sub-volume along the depth direction (skin to lung). Thesub-image is then super-imposed directly to the enhanced, whole-breastnavigator overview image by a weighted sum of the 2D projection of thenavigator overview image and the line enhanced 2D sub-image to enhancethe spiculation around the CAD ROI on the enhanced, whole-breastnavigator overview.

For likely benign lesions, such as a cyst determined by CAD, the averageintensity of several slices immediately behind (or beneath) the CAD ROIis calculated to compose a 2D sub-image. The size of the sub-volume inthe coronal plane is proportional to, but smaller than, the 2D size ofthe CAD-found ROI 2302 in the coronal slice, shown as Zone 2324. Thesub-volume 2324 is below (or beneath) the CAD-found ROI 2302, such asshown in FIG. 23A. The pixel value outside the sub-image 2324 is set tozero. The sub-image is then superimposed to the enhanced, whole-breastnavigator overview image by weighted sum between the sub-image and theenhanced, whole-breast navigator overview image to indicate the acousticenhancement of a benign lesion such as a cyst. As result, a benignlesion with acoustic enhancement behind will show in the enhanced,whole-breast navigator overview image as a dark region with a white coreinside.

A high-pass or edge enhancement filter is applied to a sub-volume 2322around a center of a CAD-found ROI 2302 in a coronal slice. The voxelvalue resulting from the high-pass filter is clipped to zero if theresulting voxel value is less than zero. A 2D sub-image is generated bythe average voxel value along the depth direction. The 2D sub-image isthen added to the enhanced, whole-breast navigator overview image by apredetermined weight. This creates a rim around the edge of the regionfor a benign lesion with well-defined border, such as a fibroadenoma.

FIGS. 24A and 24B are transversal and coronal views, respectively,illustrating CAD ROI alteration techniques, according to someembodiments. The techniques described with respect to FIGS. 23A and 23B,supra (line enhancement in zone 2320, high-pass filter in zone 2322, andsuperimposition from posterior zone 2324) can be applied to a CAD-foundROI simultaneously. In FIGS. 24A and 24B, three CAD-found ROIs 2310,2320, and 2330 are shown. By applying the alteration techniques such asdescribed with zones or sub-volumes 2320, 2322, and 2324 for eachCAD-found ROI, the graphically altered result facilitates distinguishingby a user. ROI 2410 is a typical cancer lesion, and is characterized bya spiculated margin, ill-defined border and no posterior acousticenhancement. The resulting coronal view 2410 in FIG. 24B, afteralteration, is shown as a dark hole with spiculated margin on theenhanced, whole-breast navigator overview image. ROI 2420 is a typicalcyst, with a well-defined border, very dark inside the lesion and with astrong posterior acoustic enhancement (light shadow). After alteration,the ROI 2420 in FIG. 24B is shown as a dark hole with white rim aroundits border and a white core in the center of the dark hole. ROI 2430 isa typical fibroadenoma, with well-defined border, slightly dark insidethe lesion and with no posterior acoustic enhancement. After alteration,the ROI 2430 in FIG. 24B is shown as a slightly darker hole with a whiterim around its border on the 2D guide image.

FIG. 25 illustrates aspects of a technique for detecting locally poorcoupling artifacts, according to some embodiments. In this example, analgorithm is used in a computer module to detect high decreasinggradients (i.e. light-to-dark gradients) in voxel value when moving fromthe top (skin surface) of the 3-D image volume 2500 downwards, asindicated by arrow 2502. The pixel value profile is calculated along thez-axis (depth). In poor acoustic coupling situations, the pixel valuedecreases generally linearly and the slope of decrease is much steeperthan in the surrounding tissue region. This situation can be classifiedas an artifact, and can be noted as such or voxel values from itsneighborhood can be filled in.

FIG. 26 illustrates an example of a system and method producing awhole-breast navigator image or aid starting with multiple sweeps of anultrasound transducer relative to a breast, for example as illustratedin FIG. 16. Computer modules 2602, 2604, and 2606 collect 2D originalultrasound thin-slice images from respective partly overlapping sweeps1, 2, and 3 of one or more ultrasound transducers over the breast, andrepresent the hardware involved in obtaining the images as well ascomputer storage of the resulting original scan measurements or images.A greater or lesser number of sweeps than the three that are illustratedcan be used. Each of these modules also constructs a respective 3Dstructure of the voxel values of tissue scanned with ultrasound in therespective sweep in the case of linear scanning motion of the ultrasoundtransducer or the respective scanned sector in case of rotary scan withtwo or more circumferentially spaces transducers or from a rotary scanwith a single transducer. A computer module 2608 finds in each of the 3Dstructures certain volumes that should be segmented out, such as skinand possibly a thin layer underneath, chestwall, and/or ribs, andcomputer module 2610 segments the desired scanned tissue such as thebreast tissue. Computer modules 2612, 2614, and 2616 collect and storethe 3D breast tissue voxel measurements for the respective sweeps of theultrasound transducer that were segmented in module 2610, and supply thevoxel measurements to respective filtering computer modules 2618, 2620,and 2622, which apply filtering of the types discussed above. Forexample, the filtering can include applying CAD algorithms by computermodule 2624 to the 3D structures to find likely abnormalities in thebreast tissue they represent. Alternatively, or in addition, module 2624can apply CAD algorithms to the original 2D thin-slice images and/or tothe constructed 3D structures in or from modules 2602, 2604, and 2606.The 3D structures with abnormalities found therein are supplied torespective computer modules 2628, 2630, and 2632, which apply theretofeature weighted compounding of the types discussed above to produceenhanced guide images or aids with enhanced representations of foundabnormalities for the respective sweeps. These guide images or aids canbe 2D projections of the 3D structures for the respective sweeps, andare supplied and stored in respective computer modules 2634, 2336, and2638. Then, a computer module 2640 stitches or blends the respectiveguide images or aids into a single whole-breast navigator image or aidthat can be displayed as a 2D representation of the 3D structure of thebreast and of the found enhanced abnormalities as discussed above,preferably with the pop-up 2D thin-slice image or images for respectiveabnormalities.

FIG. 27 illustrates an example of equipment and method applying CADalgorithms in producing a desired enhanced whole-breast navigator guide.Computer module 2702 applies such algorithms to a 3D structure of voxelvalues representing breast tissue to find 3D regions “I” that containlikely abnormalities and outputs a list of the found regions and foreach a probability Pi that it contains an abnormality. Computer module2704 applies a threshold Pmax to the probabilities Pi for respectivefound regions “i” thereby selecting regions that would be used toenhance abnormality representations in the ultimate whole-breastenhanced navigator aid image. Computer module 2706 then uses the resultsto alter voxel values related to the selected regions. For example, forthe i-th selected 3D region Ri(x,y,z) and its probability Pi, thepreviously found voxel values I(x,y,z) are altered into valuesI′(x,y,z)=I(x,y,z)×(Pmax−Pi)/Pmax, if the voxel (x,y,z) in that i-thregion. For voxels that are outside a region containing suspectedabnormality, the voxel value is unchanged. The process is repeated foreach voxel in each found region of a suspected abnormality. Computermodule 2708 then produces for display a 2D representation of theresulting altered 3D breast structure, for example by a minimumintensity projection of the 3D structure that includes the modifiedvoxel values I′(x,y,z).

The several examples of whole-breast navigator aids can be used fortemporal comparison with similar aids obtained for the same breast inprior studies to find changes in abnormality parameters with time or toconfirm that there have been no changes. For example, the size of afound abnormality can be compared based on two studies of the samebreast taken at different times, or the probabilities Pi can becompared.

FIG. 28 illustrates an example of equipment and method that involvetaking and using multi-mode sonographic breast measurements. In additionto the regular B-mode, breast ultrasound can be operated at other modesto further characterize breast tissue. For example, Doppler ultrasoundcan evaluate angiogenesis, while elastography can evaluate the stiffnessof a region of interest. An example of such use of several modes is tocreate a combined whole-breast enhanced navigator guide or aid. To thisend, modules 2802, 2804, 2806, and 2808 scan a breast with ultrasoundtransducers in the indicated respective modes, and from the sonographicresponses produce respective 3D structures of the scanned tissue. Onlytwo modes can be used, or more than the four indicated modes. Thesemodules produce respective 3D structures of the scanned tissue such as a3D set of voxel values. Each voxel is a representation of the ultrasoundresponse at a given mode from the corresponding location in thepatient's anatomy. Geometrically, the 3D structure can have onerectangular face, generally parallel to the chestwall, which faceclosely corresponds to the surface of the breast against which theultrasound transducer was compressed during scanning. The typicalscanned tissue includes breast tissue as well as some muscle, ribs, andpossibly lung tissue, and also contact artifacts and other structuresthat are incidental to the scan. Using all measurement from all desiredscans, computer module 2810 finds and segments out selected non-breaststructures, preferably those external to the breast such as the ribs,chest muscle, and lung regions. Scan artifacts caused by poor acousticcoupling and other problems and certain skin or thin regions near ornext to the transducer can also be segmented out in the same module oridentified for correction or corrected. After the removal of influencesof undesired structures by segmentation, the scanned 3D breast tissue(including fat, glandular tissue, and any abnormalities internal to thebreast) as represented in a 3D structure of voxels in each mode, iscollected and stored in respective computer modules 2814, 2816, 2818,and 2820, and the respective 3D structures are filtered by a group offilter modules 2822, 2824, 2826, and 2830, which are designed tosuppress noise, remaining artifacts, and to enhance abnormalities orlesions for any given mode as discussed above. As an example, thefilters for the B-Mode image can be the gradient conversion filter andline conversion filter. The gradient conversion filter is designed toenhance the dark rounded shapes, and the line conversion filter isdesigned to enhance lines radiating from a center which resembles aspeculation or architecture distortion. The gradient conversion filtercan also be applied on the elastography volume to enhance theconcentrated stiff voxels. The final step is to apply feature weightedcompounding. Computer module 2832 can apply CAD algorithms in the courseof such filtering, and/or to the respective measurements from modules2802,02804, 2806, and 2808.

Computer module 2834 applies weighted compounding to the filtered 3Dstructures. The weights, w(x,y,z) for compounding can be produced bycombining the outputs of the filters of all modes, as represented by theexpression

${w\left( {x,y,z} \right)} = {\sum\limits_{m}^{M}\;{\sum\limits_{i}^{N_{m}}\;{k_{mi}{f_{mi}\left( {x,y,z} \right)}}}}$where M is the total number of modes while Nm is the total number offilters of mode m, fmi (x, y, z) is the output of ith filter of mode m,and kmi is a constant scaling factor for ith filter of mode m. Theweight is also normalized from 0 to 1 as the probability of a voxeloverlap with a cancer lesion.

FIG. 29 illustrates equipment and methods that are otherwise the same orsimilar to FIG. 28 except that a separate whole-breast navigator guideor aid is produced for each respective ultrasound modality. The modulesthat are the same as in FIG. 28 bear the same labels and are notnumbered. The modules that are different are the multiple featureweighted compounding modules that replace the single module 2834 in FIG.28, and the plural guide image modules that replace module 2836 of FIG.28.

An example of equipment and method producing and using a whole-breastnavigator aid and related pop-ups involves segregating the ultrasoundmeasurements by frequency content into low- and high-frequencycomponents and producing a 3D structure of the scanned tissue that is aweighted combination of the low-pass (background) and high-pass (signal)components. This can be accomplished by subjecting the 3D structureproduced as discussed above to computer-processing through algorithmsproducing a background 3D structure through techniques such asnon-linear smoothing, in which case the background component is notstrictly “low-pass” in the traditional sense, but emphasizes lowfrequency image content while suppressing high-frequency content.Concurrently, computer-processing can subject the starting 3D structureto a high-pass filtering to emphasize the high-frequency (signal)content while suppressing the low-frequency content. A simple summationof these derived background and signal components of the 3D structure ofbreast voxel values should reproduce the original 3D structurefaithfully. In order to enhance the type of navigator aid discussedabove, the summation that a computer module carries out can be simplesummation outside of 3D regions of interest (ROIs) that CAD or otherfiltering has identified as discussed above but a weighted summation forthe ROIs, with the signal component emphasized in the neighborhood ofthe found ROIs. This variable-weighted 3D structure is then be subjectedto computer processing to carry out a projection such as a minimumintensity projection (MinIP) in which subtle details such asspiculations are enhanced and made more evident than in a MinI P on anunprocessed original volume. The intensity contrast of the lesion itselfis enhanced as well, possibly obviating the need to apply an explicitintensity bias, which may reduce the impact of CAD false positives onthe navigator guide image or aid.

According to some embodiments, bookmarks are added to abnormalitiesafter the user has had a chance to evaluate them. The bookmarks can becolor, possibly indicative of the importance that the user ascribes toan abnormality, a BIRAD score, a simple mark such as a circle around anexamined abnormality, and/or some other mark that can serve as areminder of the user's work with the examined images.

Processing according to the embodiments described above can be carriedout in the ultrasound engine and/or workstation equipment used in thecurrent commercial automated breast ultrasound systems, when runningprogrammed algorithms according to software that a skilled person canwrite without undue experimentation based on this patent specificationand knowledge of the processing in the commercial systems. Some of thefunctions can be implemented using firmware or hardware instead of or inaddition to software

According to some embodiments, interactive user interface methods andsystems are described that can shorten the time to view and assessimportant breast ultrasound images within a time limit of approximately3 minutes and with low oversight.

According to some embodiments, a novel CAD-driven navigator overviewimage display method and system are disclosed. The navigator overviewimage is configured to assist the readers to reduce theirreading/interpretation time and at the same time to provide comfort andconfidence such that oversights would be reduced.

According to some embodiments, the display method and system show to thereaders the abnormalities in a navigator overview image derived from 3Dvolumetric scans, where the abnormalities were image processed, withlittle or no traditional CAD involved, by displaying at each pixellocation a combined, e.g., a low average, value selected from a set ofvoxels in a voxel column that can be oriented in the chestwarddirection. According to some other embodiments, the navigator overviewimage is more CAD driven, where CAD is employed to detect and enhancethe displayed abnormalities. According to yet other embodiments, CAD isemployed to detect both malignant-looking abnormalities as well asbenign-looking abnormalities. The navigator overview image displaysadditional features, showing both malignant and benign characteristicsin a way to classify these abnormalities, to enable the readers to placehigher priority on viewing the more suspicious abnormalities. Thus, thiswould further reduce the reading/interpretation time. CAD is importantin detecting and thus reducing obvious oversights. CAD marks or CADprobability figures can be displayed anytime (before, during or afterreaders looked the navigator overview image) at the readers preferenceor as preset for the equipment.

According to some embodiments, a method and system for processing anddisplaying breast ultrasound information are provided, wherein a featureweighted volumetric navigator overview image is generated from the 3Dultrasound data volume to represent the 3D dataset with the goal ofemphasizing abnormalities found within the breast while excluding someor all non-breast tissue or structures, particularly those external tothe breast such as ribs and chest wall, and optionally skin andimmediately adjacent tissue, in accordance with the method and systemdescribed herein.

According to some embodiments, the navigator overview image is displayedin addition to and together with a display of images available incurrent commercial automated 3D breast ultrasound systems employingchestward compression scans, where a 2D original axial scan image, and a2D orthogonal (constructed to be orthogonal to the axial scan) image aredisplayed with 2D coronal thick-slice images. By clicking any exhibitedabnormality in the navigator overview image, with pre-calculated xyzcoordinates, the corresponding abnormality can show up in the 2D coronalthick-slice image, as well as at the corresponding locations in the 2Doriginal axial scan image and the orthogonal sagittal image.

According to some embodiments, the navigator overview image is displayedtogether with just the 2D original axial scan image for the quickestreview and a snippet of one or more 2D images of coronal thick-slices.It is sometimes useful to show the coronal thick-slice image, becausereaders may like to confirm their assessment by examining the presenceof spiculations of a mass nodule that only show, or show better, incomposite coronal thick-slices. The quick review of the 2D axial scanimages can be done in the manner described above.

According to some embodiments, the navigator overview image is displayedin inverted polarity. That is, in a regular display, the abnormalitiesare dark colored on relatively light breast tissue background, and inthe inverted polarity, the abnormalities are light colored on arelatively dark breast tissue background. Some readers may find it moreuseful to read the inverted polarity guides, which resemble mammograms(also with lighter colored abnormalities such as calcifications on adarker background).

According to some embodiments, the navigator overview image is generatedthrough a process of segmenting away non-breast structure and using afilter to enhance the remaining volumetric breast tissue to make theabnormalities more visible and more prominent.

According to some embodiments, the filter includes a computer aideddetection (CAD) algorithm that detects and ranks the lesions bylikelihood. This is particularly useful for very small abnormalities orlesions that show significant likelihood of being malignant by CAD, andyet the above described filter may not be enough to make these smallabnormalities as visible or prominent in the navigator overview image.

According to some embodiments, additional information is shown with anabnormality such as its size, volume, relative probability, likelihoodof being malignant, etc.

According to some embodiments, the navigator overview image is displayedon a separate monitor situated for convenient viewing, e.g., adjacent tothe display monitor of a commercial automated 3D breast ultrasoundsystem while in other embodiments all images are on the same screen,which also may show other information.

According to some embodiments, two or more navigator overview images aredisplayed, typically concurrently, each for a respective breast of thepatient or for a respective scan of a breast with an ultrasoundtransducer, while in other embodiments different images can alternate orbe superimposed, possibly with different degrees of transparency.

According to some embodiments, the navigator overview image is displayedon a separate sheet of paper to be viewed with the display monitor of acommercial automated 3D breast ultrasound system.

The computer modules or steps described in this patent specification canbe implemented in special purpose computer equipment, or in individualprogrammed computer modules, or in a lesser number of computer modulesor even a single computer system programmed in accordance with thedisclosure herein to carry out the required processes.

While several embodiments are described, it should be understood thatthe new subject matter described in this patent specification is notlimited to any one embodiment or combination of embodiments describedherein, but instead encompasses numerous alternatives, modifications,and equivalents. In addition, while numerous specific details are setforth in the following description in order to provide a thoroughunderstanding, some embodiments can be practiced without some or all ofthese details. Moreover, for the purpose of clarity, certain technicalmaterial that is known in the related art has not been described indetail in order to avoid unnecessarily obscuring the new subject matterdescribed herein. It should be clear that individual features of one orseveral of the specific embodiments described herein can be used incombination with features or other described embodiments. Further, likereference numbers and designations in the various drawings indicate likeelements.

Various modifications may be made without departing from the spirit andscope of the new methods and systems described in this patentspecification. Accordingly, the scope of this patent specification isnot limited to the above-described embodiments, but instead is definedby the claims of a patent to issue thereon in light of their full scopeof equivalents.

What is claimed is:
 1. A system for ultrasound examination of apatient's breast, comprising: an ultrasound transducer compressingchestwardly a breast of a recumbent patient and scanning the breast withone or more ultrasound transducers to thereby produce originaltwo-dimensional (2D) ultrasound images of the breast that conform toplanes extending in chestward directions; a first programmed computerprocessor module receiving the original images and configured to applycomputer processing algorithms thereto to produce one or morethree-dimensional (3D) images representing ultrasound responses ofrespective volume elements (voxels) of the scanned breast; a secondprogrammed computer module configured to apply computer processingalgorithms to at least one of (i) the 2D images and (ii) the one or more3D images, to thereby find abnormalities in the entire 3D breast tissuethat is inward of regions of skin, ribs, and pectoral muscle, includingby comparing ultrasound responses for portions of the breast withultrasound responses for other portions of the breast and taking intoaccount shape properties of potential abnormalities; a third programmedcomputer module configured to apply computer processing algorithms to atleast one of (i) said 2D images and (ii) said one or more 3D images tothereby produce a whole-breast navigator structure depicting the entire3D breast tissue that is inward of said regions; wherein said wholebreast navigator structure comprises a selected 2D projection of saidentire 3D breast tissue that is inward of said regions and of theabnormalities found by the second programmed computer module; whereinthe 2D projection of the whole breast navigator structure shows thelocations of the abnormalities in two dimensions but not necessarily atrue shape of the abnormalities; and a computer display configured to:produce and display a depiction of the whole-breast navigator structurewith abnormalities therein; and respond automatically to user inputregarding an abnormality in the whole-breast navigator structure byproducing and concurrently displaying pop-up depictions of theabnormality as it appears in a coronal image of the scanned tissue thathas a selected thickness and in at least one of the 2D original imagesthat also contains the same abnormality.
 2. The system of claim 1 inwhich the third programmed computer module is configured to boostrepresentations of found tissue abnormalities by making the displayedlocations of likely malignant abnormalities darker or lighter in thenavigator structure than if not boosted.
 3. The system of claim 1 inwhich the third programmed computer module is configured to boostconspicuity of representations of locations of abnormalities that arelikely speculations in the navigator structure.
 4. The system of claim 1in which the third programmed computer module is configured to boostconspicuity of representations of abnormalities that are a likely cystand enhance the location of an image of a cyst in the displayednavigator structure by placing a spot therein that differs from aremainder of the cyst image.
 5. The system of claim 1 in which the thirdprogrammed computer module is configured to detect and remove influencesof ultrasound responses resulting from poor ultrasoundtransducer-to-breast coupling.
 6. The system of claim 1 in which thethird programmed computer module is configured to produce thewhole-breast navigator structure through a process comprising assigningto a pixel in a projection of the navigator structure a value related tothe darkest voxel value in a related column of voxel values.
 7. Thesystem of claim 1 in which the third programmed computer module isconfigured to produce the whole-breast navigator structure through aprocess comprising assigning to a pixel in a projection of the navigatorstructure a value related to voxel values along a stretch of 1-3 mmcontaining the darkest voxel values of a related column of voxel values.8. The system of claim 1 in which the third programmed computer moduleis configured to produce the whole-breast navigator structure through aprocess comprising assigning to a pixel in a projection of the navigatorstructure a value related to only some of the voxel values of a relatedcolumn of voxel values.
 9. The system of claim 1 in which the ultrasoundtransducer compresses and scans the breast of a supine patient.
 10. Asystem for automated ultrasound examination of one or both of apatient's breasts, comprising: a source of a sonographic responseacquired by chestwardly compressing a breast of a recumbent patient andscanning the compressed breast tissue with ultrasound emitted andreceived by an ultrasound transducer electrically and/or mechanicallydriven for a scanning motion relative to the breast; a programmedcomputer processor configured to apply computer image processingalgorithms to the sonographic response thereby producing a whole breastthree-dimensional (3D) structure representing ultrasound responses forvolume elements (voxels) of the scanned breast; said processor beingconfigured to apply computer processing algorithms to (i) segment outinfluences of non-breast tissue interactions with ultrasound in saidscanning, (ii) find tissue abnormalities in the whole-breast 3Dstructure remaining after said segmenting, including by comparing asonographic response for portions of the breast with a sonographicresponse for other portions of the breast and accounting for shapeproperties of potential abnormalities; said processor thereby producinga single whole-breast navigator overview image per breast, and beingconfigured to apply filtering algorithms enhancing representations ofsuspected abnormalities to thereby produce conspicuity enhancements ofone or more of the found tissue abnormalities in each overview image;and a computerized display configured to display the single whole-breastnavigator overview image per breast in association with selected otherimages automatically selected and generated from the sonographicresponse that include representations of at least one abnormality foundin the navigator overview image.
 11. The system of claim 10 in which thesource of the sonographic response is configured to provide thesonographic response from multiple scans with ultrasound of each breast,the processor is configured to obtain plural enhanced, whole-breastnavigator overview images related to the respective multiple scans ofeach breast, and the display is configured to concurrently display theplural enhanced, whole-breast navigator overview images of each breastand automatically selected pop-up coronal thick-slice and chestwardlyoriented thin-slice images containing a selected abnormality present inthe navigator overview images, wherein said thick-slice image representsa slice of the patient's breast that is thicker than a slice of thebreast represented by said thin-slice image.
 12. The system of claim 10in which the processor is configured to form reduced-size images of theenhanced, whole-breast navigator overview images, and the display isconfigured to concurrently display at least one whole-breast navigatoroverview image together with the reduced size images and at least onethick-slice coronal image and at least one thin-slice image of thebreast containing an abnormality present in the navigator image, whereinsaid thick-slice image represents a slice of the patient's breast thatis thicker than a slice of the breast represented by said thin-sliceimage.
 13. A system for automated ultrasound examination of a patient'sbreasts, comprising: a source of sonographic responses each acquired bycompressing the patient's breasts chestwardly while the patient isrecumbent and scanning the compressed breast tissue with one or moreultrasound transducers electrically or mechanically driven to scan thebreasts; a programmed computer processor configured to apply computerimage processing algorithms to the sonographic responses therebyproducing a plurality of whole-breast navigator overview images eachrepresenting a three-dimensional breast volume with abnormalitiestherein found through filtering with said algorithms; said processorbeing configured to produce each of said plurality of whole-breastnavigator overview images by (i) producing from said sonographicresponses a three-dimensional (3D) structure representing volumeelements (voxels) of scanned tissue, (ii) segmenting out influences ofnon-breast tissue in said sonographic responses and finding tissueabnormalities in the remaining whole-breast 3D structure, including bycomparing sonographic responses for portions of the breast withsonographic responses for other portions of the breast and accountingfor shape properties of potential abnormalities, and (iii) producingconspicuity enhancements of at least some of the found tissueabnormalities; a computerized display configured to display two or moreof the plurality of whole-breast navigator overview images to a user,the processor being further configured to respond to a selection by auser of a region of interest (ROI) in a whole breast navigator overviewimage to cause a display of one or more other images generated from thesonographic responses that are associated with the user-selected ROI,the one or more other images including at least one thick-slice image.14. The system of claim 13 wherein the selection of the ROI by the useris made by dwelling a pointing device on the ROI.
 15. The system ofclaim 13 wherein the one or more other images further include at least aportion of an original two-dimensional thin-slice scan image, whereinsaid at least one thick-slice image represents a slice of the patient'sbreast that is thicker than a slice of the breast represented by saidthin-slice scan image.
 16. The system of claim 13 wherein the processoris further configured to respond to a user input to successively displayadditional images generated from the sonographic response in thevicinity of the ROI.
 17. The system of claim 13 in which the ultrasoundtransducer compresses and scans the breasts of a supine patient.
 18. Amethod of ultrasound examination of a patient's breast, comprising:compressing a patient's breast chestwardly while the patient isrecumbent and scanning the breast with an ultrasound transducer througha gel-impregnated membrane in a scanning motion relative to the breastwhile sending ultrasound energy into the breast and receiving ultrasoundenergy from scanned tissue, thereby producing ultrasound responses forbreast slices that conform to planes extending in chestward directions;applying computer processing to the ultrasound responses therebyproducing a three-dimensional (3D) structure representing sonographicresponse characteristics of volume elements (voxels) of scanned tissue;applying computer processing algorithms to at least one of (i) theultrasound responses and (ii) the 3D structure, thereby segmenting outinfluences of selected scanned tissue and finding tissue abnormalitiesin the remaining 3D structure, including by comparing ultrasoundresponses of portions of the breast with those of other portions of thebreast; applying further computer processing algorithms to the remaining3D structure thereby producing enhancements of at least some of thefound tissue abnormalities; applying further computer processing to the3D structure thereby producing an enhanced whole-breast navigatorstructure depicting the scanned breast and abnormalities therein thathave been enhanced; wherein the enhanced whole-breast navigatorstructure depicts in two dimensions the entire breast tissue remainingafter said segmenting out; producing and displaying a depiction of theenhanced whole-breast navigator structure with abnormalities therein;and responding to user input regarding an abnormality in thewhole-breast navigator structure by producing and concurrentlydisplaying pop-up depictions of the abnormality as it appears in acoronal thick-slice image of the scanned tissue that has a selectedthickness and in at least one thin-slice chestwardly oriented image,wherein said thick-slice image represents a slice of the patient'sbreast that is thicker than a slice of the breast represented by saidthin-slice image.
 19. The method of claim 18 in which the producing ofenhancements comprises boosting representations of found tissueabnormalities by making likely malignant abnormalities darker or lighterin the navigator structure than if not boosted.
 20. The method of claim18 in which the producing of enhancements comprises boostingrepresentations of abnormalities that represent likely speculations inthe navigator structure.
 21. The method of claim 18 in which thecompressing step comprises compressing a supine patient's breast.